The present invention relates to solid-state imaging apparatus in which a solid-state imaging device chip and an electric signal outputting member are connected to each other, and more particularly relates to a solid state imaging apparatus using a flexible board as the member for outputting electric signal.
In general, a reduction in size is sought in the packaging of solid-state imaging device. Especially in the medical field, for example, the reduction in size of imaging unit using solid-state imaging device depends largely on how such packaging form can be reduced in size. In connection with the downsizing, attempts have been made in the packaging form using a flexible board so as to narrow pitch in the wiring pattern within the flexible board. As a result, the form of packaging has become complicated.
Under the circumstances, disclosure has been made in Japanese Patent Application Laid-Open 2003-133654 of an example of solid-state imaging apparatus where solid-state imaging device for use for example in medicine is mounted on a flexible board. FIGS. 1A, 1B show a prior-art solid-state imaging apparatus as disclosed in the publication. This prior-art example is constructed such that, after connecting a bump 23 formed on an electrode 22 provided on solid-state imaging device 21 to an inner lead 29 of flexible board 24 as shown in FIG. 1A, the flexible board 24 is bent as shown in FIG. 1B along a side face 21a at an end portion of the solid-state imaging device 21. A thin portion 28 is formed on the flexible board 24 in a portion of its base film 25 corresponding to an extent from the angular portion to the side face of the solid-state imaging device 21. The thin portion 28 is formed to have a smaller thickness than the bump 23 formed on the electrode 22 over the solid-state imaging device 21. It is thereby presumably possible not to hinder connection of the flexible board 24 to the solid-state imaging device 21, and edge short can be prevented even when the inner lead 29 is bent. It should be noted that what is denoted by numeral 26 in FIGS. 1A, 1B is a wiring pattern within the flexible board 24.
With the above described prior-art technique for mounting solid-state imaging apparatus onto a flexible board, however, tenacity against bend occurs due to the fact that the inner lead 29 exists at the portion where the thin portion 28 of base film 25 of flexible board 24 is formed. Accordingly, when the flexible board 24 is bent along the side face 21a of the solid-state imaging device 21, its bendability may be hindered to result a greater radius of curvature of bend as shown in FIG. 2. For this reason, though it is effective in preventing an edge short, size of the bend portion becomes an addition of what corresponds to a curved portion α to the thickness “d” of the flexible board 21 so that there is a possibility of being unable to facilitate a reduction in size of the terminal end portion as of an imaging unit. Also, a special processing step is required to form the thin portion 28 on the base film 25 of the flexible board 24. Further, work is complicated for the construction where the inner lead 29 is bent, which causes a lowered yield. Furthermore, since the bend portion is always under pressure, reliability might be lowered.